ARIA7: Using aria-labelledby for link purpose

Important Information about Techniques

See Understanding Techniques for WCAG Success Criteria for important information about the usage of these informative techniques and how they relate to the normative WCAG 2.0 success criteria. The Applicability section explains the scope of the technique, and the presence of techniques for a specific technology does not imply that the technology can be used in all situations to create content that meets WCAG 2.0.

User Agent and Assistive Technology Support Notes

Description

With the aria-labelledby attribute, authors can use a visible text element on the page as a label for a focusable element (a form control or a link). For example, a "read more..." link could be associated with the text of the heading of the preceding section to make the purpose of the link unambiguous (see example 1).

When associating text to a focusable element with the help of aria-labelledby, the target text element is given an ID which is referenced in the value of the aria-labelledby attribute of the focusable element.

It is also possible to use several text elements on the page as a label for a focusable element. Each of the text elements used must be given a unique ID which is referenced as a string of IDs (IDREF) in the value of the aria-labelledby attribute. The label text should then be concatenated following the order of IDs in the value of the aria-labelledby attribute.

When applied on links, aria-labelledby can be used to identify the purpose of a link that may be readily apparent for sighted users, but less obvious for screen reader users.

The specified behavior of aria-labelledby is that the associated label text is announced instead of the link text (not in addition to the link text). When the link text itself should be included in the label text, the ID of the link should be referenced as well in the string of IDs forming the value of the aria-labelledby attribute.

Examples

Example 1: Providing additional information for links

This example will mean that the link text as shown on screen is then used as the start of the accessible name for the link. Popular screen readers like JAWS and NVDA will announce this as:
"Read more ...Storms hit east coast" and will display that same text in the links list which is very useful for screen reader users who may browse by links.

Example 2: Concatenating link text from multiple sources

There may be cases where an author will placed a tag around a section of code that will be referenced.

Note: The use of tabindex="-1" on the span element is not meant to support focusing by scripts - here, it merely serves to ensure that some browsers (IE9, IE10) will include the span element in the accessibility tree, thus making it available for reference by aria-labelledby. For more details see Accessible HTML Elements.

Related Techniques

Tests

Procedure

Check that each ID in the value of the aria-labelledby attribute matches an ID of a text element used as part of the link purpose.

Check that the combined value of the text referenced by the one or more ID's in the aria-labelledby attribute properly describes the purpose of the link element.

Expected Results

Checks #1 and #2 are true.

If this is a sufficient technique for a success criterion, failing this test procedure does not necessarily mean that the success criterion has not been satisfied in some other way, only that this technique has not been successfully implemented and can not be used to claim conformance.